1. Field of Invention
This invention generally relates to the field of digital computer systems and particularly in the field of video and multimedia computer servers and systems, along with the associated delivery of such content to a user/subscriber premises.
2. Description of the Related Art
Distribution of full motion video and audio data has evolved from early television broadcasting to meet viewer demand. Earliest video distribution was by point-to-point wiring between a camera and a video monitor. This was followed by scheduled television broadcasting of programming over the public air waves. In the 1960s, Community Antenna Television (CATV) was chartered to provide off-air television signals to viewers in broadcast reception fringe areas. Later, under FCC regulation, the CATV industry was required to provide local access and original programming in addition to off-air broadcast signal distribution.
In response, several sources of cable network programming were established. Because of the wide bandwidth available on cable television systems, additional channels were made available for the new programming. However, programming was generally prescheduled, with the view left to tune to the designated channel at the appointed time to view a particular program.
To increase revenues, cable television systems have initiated distribution of premium channels viewable only by users/subscribers having appropriate descramblers. The descramblers are tuned to receive only premium channels, descramble the video and audio information and supply a signal capable of reception on a standard television set.
Pay-per-view programs, which evolved later, include recently released movies, live concerts, popular sporting events, etc. Users/subscribers wishing to view a pay-per-view program place an order with the cable operator. At the designated time, the user subscriber's descrambler is activated to permit viewing of the pay-per-view programming. However, the user/subscriber is restricted to viewing the programming at the scheduled time. There is no capability of delivering programming to a user/subscriber on demand, that is, immediately or at a user/subscriber-specified time and date.
In the early 1980s, technological advances resulted in the proliferation of Video Cassette Recorders (VCR), establishing a second course for video programming distribution. Pre-recorded video programs are now available for sale and rental to VCR owners. Using a VCR, the viewer selects from among many titles available for sale and rental, and views the program when convenient. The VCR owner further has the capability to selectively view the programming using special functions of the VCR, such as pause, fast forward, reverse, slow motion, etc. The viewer can thus manipulate and replay portions of the program at will.
The penalty for this convenience, however, is in the necessity to travel to the local video rental/sales store, if necessary wait for a popular video program tape to become available, once the program is obtained return home to view it and then revisit the video store to return the tape.
Telephone lines have been suggested as an alternative means of video distribution in Goodman et al., U.S. Pat. No. 5,010,399 and Kleinerman, U.S. Pat. No. 4,849,811. However, systems using the public switched telephone network (PSTN) are often bandwidth limited, providing only still frame or video conferencing capabilities. Because telephone system carriers for the most part use the PSTN only for connectivity between users/subscribers, there is no capability for dynamic routing of digitized video without dedicated leased, wide bandwidth circuits. Telephone line-based systems also fail to provide acceptable VCR type functional control of the programming.
Alternatively, the Internet, World Wide Web, cable and satellite delivery systems continue to provide growing bandwidth communication channels which will soon interconnect most households and business and promise to provide many services to connected users. These services include instant access to large databases of financial, educational and other multimedia information, in addition to real-time interaction with virtual communities of people with similar interests. Among the services that will be available, one that has received a great deal of corporate and media attention is the provision of video on demand (VOD).
VOD holds out the promise that almost every movie ever made will be available to a user of the service at any time. Instead of driving to a video rental store and selecting a movie, users will be able to select any movie stored in the multimedia content server system's video library and have that movie delivered to them over the Internet, or by cable or satellite systems.
Before the promise of VOD can be realized, many problems must be solved. Even a relatively short film of two hours duration contains approximately 2.2×1010 bits of data. Standard methods to compress and store the vast quantity of data contained in a film library of thousands of titles must be agreed upon. Even after the data has been captured and stored, there is no industry agreement as to what system will be needed to deliver the stored data to users.
Any proposed system must satisfy rigorous user demands. Users will want whatever film they have selected delivered to them quickly. They will also want the ability to start and stop the film at any point, as well as the ability to fast forward (FF) and fast reverse (FR) the film at will. According to existing prior art systems, this typically is done by sending a unique stream of data (i.e., the movie) to each subscriber. However, because thousands of people could be watching the movie at the same time, providing these capabilities to every user at any time would place enormous demands on the system's storage units, internal buses, and processing units. Even the enormous bandwidth of fiber optic cable may be exceeded.
Additionally, some two-way communication between the user and the system is necessary to communicate users' requests, as well as billing information and the like. This two-way communication places additional burdens on the system.
Programming-on-demand cable systems have been proposed which allow any one of a plurality of individual users to request any one of a plurality of video programs they wish to view (time delayed) from the server's library of programs, and permits the requested program to be available for subsequent viewing on a conventional television set at the user's location following a request initiated by the user/subscriber. Each program is pre-stored in a digital storage device and is selectable by a host computer or server system at the head end facility in response to an address signal transmitted from the user/subscriber. The host computer in conjunction with other communication and data processing hardware and software transmits the video program as digital data at a high non-real-time rate over a high bandwidth system, such as a fiber optic line network, to a data receiving station at the user/subscriber's premises, e.g., set-top-box (STB). The STB then stores the digital content for subsequent real-time transmission to the user's television set. Such systems permit the user/subscriber to view any one of a number of programs transmitted on a non-real-time basis and also allow the user to store the transmitted program on the STB for an indefinite period of time for viewing at a later date.
Various methods have been proposed for transmitting the programs on a non-real-time basis. For example, referring to FIG. 1, a typical video server (VS), as disclosed by Verhille et al. in U.S. Pat. No. 5,539,448, is used in a video on demand network wherein video signals are transferred over a communication network (TSY) from the video server to respective terminals connected to the network. The system includes digital storage facilities (DSF), a server control means (SCM), a broadband switch (BS) having first ports (VP1/VPY) to which the storage facilities (DSF) are coupled, second ports (CL) coupled to the communication network (TSY) and a third port (CP) to which the server control means (SCM) is coupled. The server control means (SCM) controls the transfer of digital video content from the storage facilities (DSF) and through the switch (BS) and the communication network (TSY) to the terminals. The broadband switch (BS) also has set of fourth ports (CP1/CPX) to which systems adapters (SYA1/SYAX) are coupled to adapt the video signals to a format which is compatible with the communication network. The server control means (SCM) performs the transfer of video signals firstly from the digital storage facilities (DSF) to the system adapters (SYA1/SYAS) through the switch (BS) and then from the adapter means to the terminals via the communication network (TSY). The system adapters include channel memories and adapters to perform rate and format adaptation of the video signals respectively. The channel memories and the adapters can be directly and separately coupled to the broadband switch.
In operation, video servers like that of Verhille et al. receive user requests transmitted from multiple users' STBs through a distribution network to the server. The requests are routed on to a real time controller, which furthers them to a system controller. If the system controller determines that a given user is permitted access and that the requested video data is in the storage system, the system controller orders the real time controller to permit user access and tells the real time controller where the video data is stored.
The server facility transmits coded digital video data over a broadband PSTN which supplies connectivity to the facility. A user/subscriber may use either a standard telephone instrument over the PSTN or a dedicated control device over an ISDN packet network to order the video programming. Such a device is located at the television set of the user/subscriber and permits a display of the program menu on the television screen.
Connectivity between the server facility and the user/subscriber for transmission of video data is provided by an asymmetrical digital user/subscriber line (ADSL) system. ADSL interface units perform multiplexing of digital video information with voice information to be transmitted to the user/subscriber and support transmission on the ISDN packet data network of a reverse control channel from the user/subscriber to the server facility.
However, conventional video on demand services do not include an integral and comprehensive library of video program material that can be stored directly on the user/subscriber's STB, and hence enable only limited storage capabilities for video and audio data supplied by the server. Enhanced scheduling functionality is required to efficiently support multiple users/subscribers over a temporally diverse programming range. Furthermore, to support network management and enable instantaneous access to multimedia content, a need remains for a system which does not require dynamic interacting with network facilities or to reconfigure network resources in real-time in response to multimedia content requests by plural users/subscribers.